PROJECT SUMMARY/ABSTRACT Our ability to investigate the genetic basis of neuromuscular disease has entered a new era as advances in sequencing allow more rapid identification of underlying mutations. Mutations identified in patients can be moved quickly to model organisms, such as mice, for the detailed mechanistic studies not possible in patients. The number of available mouse models of neuromuscular disease is increasing constantly, as is the repertoire of available molecular genetics tools. By comparison, there is a relative lack of sophisticated tools for in vivo phenotypic characterization in mice with neuromuscular disease. In the clinic, electromyography (EMG) and nerve action potentials (NAP) data are routinely collected from patients for diagnosis and research. These measures of neuromuscular performance are particularly useful because they can be repeated and used to monitor progression or response to treatment over time. We propose to develop similar capabilities in mice by refining existing implantable technology that will allow longitudinal recording of EMG and NAP in untethered, freely moving mice.